This disclosure relates to an aircraft wing airfoil surface control system. More particularly, the disclosure relates to an articulable rotational coupling having a universal joint.
Universal joints are used to transmit rotational torque over small angles in many driveline applications. In adverse environments, a boot over the universal joint is used to keep moisture and dirt off the working elements of the universal joint and to help retain the lubrication around the universal joint. Damage to the universal joint boot often occurs when the universal joint is flexed beyond the angle for which the universal joint boot was designed. Undesirably large angles may result during installation of the driveshaft or torque tube assembly into the aircraft or if one of the torque tubes breaks during operation, for example. This results in the universal joint boot becoming torn or disengaged from the retention ring on the end of the universal joint boot. As a result, dirt and moisture may enter the universal joint and the grease may leak from the universal joint during rotation resulting in corrosion and/or premature wear.